With the recent Manhattanization of buildings, various elevators capable of rapidly and efficiently carrying a lot of passengers are developed and installed. As well known, the elevator is a transporting means for safely carrying passengers or loads while vertically linearly moving along a shaft (called an enclosed space) that is vertical formed in a building.
Conventional elevators generally include guide rails that is firmly vertically installed in a shaft in a building, a cage that moves up and down along the guide rails, a wire rope that is connected to the cage at one end thereof, a counterweight that is connected to the other end of the wire rope and moves along the guide rails installed vertically at one side of the shaft without overlapping a movement path of the cage in the opposite direction of the moving direction of the cage, and a driving motor that is installed at the uppermost portion of the shaft, is in frictional contact with the wire rope, and raises/lowers the cage and the counterweight by means of forward/backward rotation.
In the case of the conventional elevator systems, only a single driving motor is used, and thus the driving motor has a large size. To operate the large driving motor, a machine room in which the driving motor and related components are installed on the rooftop of the building should be provided, and thus there is a problem in that the space is inefficiently used. Further, a driving motor having high torque and output is used, which increases manufacturing and maintenance costs.
To solve these problems, an elevator system is disclosed in Korean Unexamined Patent Application Publication No. 10-2010-0110555.
Such an elevator system includes a plurality of driving motors, a cage that is raised/lowered by the driving motors, a counterweight that is operated opposite to the raising/lowering operation of the cage, a wire rope that is connected to the driving motors, the cage, and the counterweight at the same time, a sensing unit that measures weight of passengers and loads mounted in the cage, and a controller that controls the plurality of driving motors so as to be selectively operated.
However, this elevator system is operated by the plurality of driving motors, and thus requires much power for driving the plurality of driving motors.